NO20111220A1 - Use of aluminum phosphate, polyphosphate and metaphosphate particles in paper coating applications - Google Patents

Abstract

Provided herein are coating compositions for paper comprising aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and / or aluminum polyphosphate pigments. Methods for preparing and using the compositions are described.

Description

USE OF ALUMINUM PHOSPHATE, POLYPHOSPHATE AND METAPHOSPHATE PARTICLES IN PAPER COATING APPLICATIONS

FIELD OF THE INVENTION

Provided herein are coated papers, including high bulk coated paper, comprising a coating composition on at least one side of a base paper, wherein the coating composition comprises aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and/or aluminum polyphosphate particles. Procedures for the production and use of the coated paper and the coating compositions are also described.

BACKGROUND OF THE INVENTION

Coated paper is used for a wide range of products including packaging, board art paper, brochures, magazines, catalogs and flyers. Such coated paper is required to provide a variety of properties, including whiteness, opacity and sheet gloss, as well as printing performance. Examples of coated papers and coating compositions are described in US patents no. 7,425,246; 7,407,700; 7,160,419; 7,435,483 and 7,201,826, all of which are incorporated by reference in their entirety.

Coating compositions are generally prepared by forming a liquid aqueous suspension of particulate pigment material together with a binder and other optional ingredients. The coating can suitably be applied by different coating equipment used for the production of coated paper. The pigments for use in the coating compositions include titanium dioxide, zeolite and others. However, titanium dioxide is known to be an expensive pigment to manufacture.

There is a continued need for coated papers with improved properties and cost-effective coating compositions.

SUMMARY OF THE INVENTION

Provided herein are coated papers comprising a coating composition on at least one side of a base paper, wherein the coating composition comprises aluminum phosphate, aluminum metaphosphate, aluminum otrophosphate and/or aluminum polyphosphate particles. In certain embodiments, the aluminum phosphate compositions can be used for coating a paper producing a coated paper with improved characteristics over existing uncoated and coated papers made with other pigments.

In certain embodiments, a thicker, coated paper is provided herein. In one aspect, there is provided a method of making a high bulk coated paper wherein the coating forms a smaller portion of the total thickness and the paper base forms a greater portion of the total thickness than conventionally manufactured coated paper of the same weight. The method includes the steps of using pulp composition with a high percentage, say above 50%, and preferably in a range of 55 to 75%, with a target of 60 to 65%, of mechanical pulp, or other similar fibrous pulps known in the art, applying this pulp composition to two or double wire paper machines, with, for example, a "gap former", coating the paper with a coating containing an aluminum phosphate pigment, in one embodiment, in a concentration of 4 or more parts, or 7 or more parts per 100 parts coating pigment, and calender the coated paper at a load less than conventional super calender load. In one embodiment, there is provided herein a light weight quality coated paper such as ultra light weight coated paper.

In certain embodiments, the coating compositions further include a solvent, one or more additives, and optionally one or more additional pigments, such as calcium carbonate, including ground calcium carbonate (GCC), precipitated calcium carbonate (PCC), calcined kaolin, hydrous kaolin, delaminated clay, kaolin clay, talc, mica, dolomite, silica, silicates, zeolite, gypsum, satin white, titanium oxide, titanium dioxide, calcium sulphate, barite white or barium sulphate, aluminum trihydrate, plastic pigment and combinations thereof. Suitable additives, for example, may be selected from binders, lubricants, dispersants, leveling agents, antifoams, wetting agents, optical brighteners, biocides, crosslinking agents, water retention agents, viscosity modifiers or thickeners and combinations thereof. In certain embodiments, the solvent is water.

In general, the amount of aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and/or aluminum polyphosphate pigment present in the coating compositions described herein can vary widely depending on the desired properties in the final coated paper product. In certain embodiments, the aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate, and/or aluminum polyphosphate pigment provided herein is used in the composition in an amount greater than about 1%, 3%, 5%, 7%, 10%, 12%, 15%, 20 %, 25%, 30%, 40% or 50% total weight of solids in the coating composition. In certain embodiments, the coating compositions described herein are aqueous compositions.

The coated paper provided herein is suitable for a variety of printing applications including Giclee printing, color copying, xerography, screen printing, gravure, sublimation, flexography, inkjet printing, photography, offset printing, including roll offset printing, electrophotographic printing, image registration paper for thermal transfer registration, inkjet registration and other applications.

In one aspect, provided herein are inkjet papers and papers for digital printing comprising the aluminum phosphate compositions.

In another aspect, there is provided herein a coated coverboard for direct flexography after printing to prevent rubbing and to improve image fidelity comprising the aluminum phosphate compositions. In certain embodiments, aluminum phosphate compositions are used in this application in combination with compositions comprising other pigments known in the art.

In another aspect, there is provided herein an ultralight weight coated publication paper.

It is yet another aspect, provided herein is gravure printing paper comprising the aluminum phosphate compositions.

The coated paper provided herein has improved properties, including improved gloss, smoothness, opacity and/or whiteness. In certain embodiments, the coated paper provided herein has a coating gloss equal to or greater than about 20% at 75° as measured by TAPPI test method T480 om-92.1 certain embodiments, the coated paper provided herein has a smoothness of less than 5.0, 4.0, 3.0, 2.0 or 1.0 as measured using TAPPI test method for Parker Print Surface: T555 om-99. In certain embodiments, the coated paper has an opacity of greater than 80% as measured using TAPPI test method T425 om-91.1 certain embodiments, the coated paper has whiteness levels greater than about 70%, 73%, 75%, 77%, 80 %, 85% or 90% GE degree of whiteness as measured using TAPPI test method T452 about 92.

In one aspect, the aluminum phosphate compositions used in the coated paper provided herein have improved rheology compared to silica and/or other specialty pigments. In certain embodiments, the aluminum phosphate compositions improve coating fluidity and/or improve energy consumption during drying. In other embodiments, the aluminum phosphate compositions are in the form of aqueous slurries with a higher percentage of solids and good shear thinning rheology compared to existing compositions. Accordingly, the aluminum phosphate compositions provided herein result in faster drying rates on the machine due to coatings with a higher percentage of solids than existing compositions resulting in lower drying costs and reduced pressure rubbing.

In certain embodiments, the aluminum phosphate compositions have improved coating flow on the machine and therefore improved production rates over existing compositions. In other embodiments, the aluminum phosphate compositions have low Einlehner wear resulting in reduced wear on process equipment and no metallic marks are left on the paper at the gripper bars.

In one embodiment, the aluminum phosphate compositions herein comprise higher solids composition compared to existing compositions. In another embodiment, the aluminum phosphate compositions herein provide a low bulk density.

In another embodiment, the aluminum phosphate compositions provided herein coat paper with substantially no dusting, have improved optical/reflective densities for four-color cyan, magenta, yellow, black (CMYK) inkjet printing, have a narrow particle size distribution with low fines, and/ or have improved first pass retention in paper machine trials compared to existing compositions.

In yet another embodiment, the aluminum phosphate compositions provided herein enable lighter coating weights due to internal void volume.

In certain embodiments, the aluminum phosphate compositions provided herein have improved ink jet printing density, improved ink receptivity in printing papers and/or improved opacity.

In one embodiment, the aluminum phosphate compositions herein provide less pick-up and reduced roughening of the base sheet during application, resulting in a more evenly coated sheet.

In another embodiment, the aluminum phosphate compositions provided herein allow higher operating speeds and higher production rates. In yet another embodiment, the aluminum phosphate compositions herein provide the ability to coat on high speed paper machines rather than only on low speed off-machine coating lines which reduces waste and costs.

In one embodiment, the aluminum phosphate compositions provided herein can act as fillers in newsprint to prevent penetration, and as fillers in technical specialty papers such as corrosion protection, gas filtration, filter and absorbent papers.

In another embodiment, the aluminum phosphate compositions provided herein are used as microparticulate retention aids, deinking aids in combination with flotation-washing systems, or coefficient of friction (COF) control aids in recycled tire carton.

BRIEF DESCRIPTION OF FIGURES

Figure 1 provides a comparison of low shear viscosity at 100 RPM for coating compositions comprising aluminum phosphate pigments and the titanium dioxide pigments. Figure 2 provides a comparison of high shear viscosity at 100 RPM for coating compositions comprising aluminum phosphate pigments and the titanium dioxide pigments. Figure 3 provides low shear viscosity at 100 RPM for coating formulations obtained by gradual replacement of TiO 2 with aluminum phosphate pigment. Figure 4 provides high shear viscosity at 100 RPM for coating formulations obtained by gradual replacement of TiO 2 with aluminum phosphate pigment. Figure 5 provides a comparison of water retention properties for coating compositions comprising aluminum phosphate pigments and the titanium dioxide pigments. Figure 6 provides an effect on water retention for the coating compositions when replacing TiO 2 with aluminum phosphate. Figure 7 provides a comparison of opacity for paper coated with compositions comprising aluminum phosphate pigments and the titanium dioxide pigments prior to calendering. Figure 8 provides a comparison of opacity for paper coated with compositions comprising aluminum phosphate pigments and the titanium dioxide pigments after calendering. Figure 9 provides an effect of replacing TiO 2 with aluminum phosphate pigments on coated paper opacity. Figure 10 provides a comparison of whiteness for paper coated with compositions comprising aluminum phosphate pigments and the titanium dioxide pigments before and after calendering. Figure 11 provides an effect of replacing TiO 2 with aluminum phosphate pigments on the degree of whiteness of coated paper. Figure 12 provides a comparison of gloss of paper coated with compositions comprising aluminum phosphate pigments and the titanium dioxide pigments. Figure 13 provides an effect of replacing TiO 2 with aluminum phosphate pigments on the gloss of coated paper. Figure 14 provides a comparison of surface strength of paper coated with compositions comprising aluminum phosphate pigments and the titanium dioxide pigments. Figure 15 provides an effect of replacing TiO 2 with aluminum phosphate pigments on surface strength of coated paper. Figure 16 provides a comparison of surface coverage for compositions comprising aluminum phosphate pigments and the titanium dioxide pigments.

Figure 17 shows a plot of gloss in relation to coating conditions.

Figure 18 shows a plot of smoothness in relation to coating conditions. Figure 19 shows a plot of degree of whiteness in relation to coating conditions. Figure 20 shows a plot of CD (transverse direction) gloss in relation to coating conditions. Figure 21 shows a plot of MD (machine direction) gloss versus coating conditions. Figure 22 shows a plot of calendered degree of whiteness in relation to coating conditions. Figure 23 shows a plot of calendered smoothness in relation to coating conditions. Figure 24 shows a plot of calendered opacity in relation to coating conditions. Figure 25 describes a coating preparation schematically for control coating (formulation #1). Figure 26 describes a coating preparation schematically for coating with 5 parts substitution (formulation #2). Figure 27 describes a coating preparation schematically for coating with 10 parts substitution (formulation #3). Figure 28 shows a plot of degree of whiteness against the amount of aluminum phosphate pigment, without the addition of PVOH. Figure 29 shows a plot of degree of whiteness against the amount of aluminum phosphate pigment, with the addition of PVOH. Figure 30 shows a plot of fluorescence numbers against the amount of aluminum phosphate pigment, without the addition of PVOH. Figure 31 shows a plot of fluorescence numbers against the amount of aluminum phosphate pigment, with the addition of PVOH.

In the Figures and Examples 1-3, the aluminum phosphate pigment is also referred to as Pigment X or PX.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

In the following description, all numbers presented herein are approximate values, regardless of whether the word "about" or "approximately" is used in connection with them. They can vary by 1 percent, 2 percent, 5 percent, or, sometimes, 10 to 20 percent. Each time a numerical range with a lower limit value, R<L>and a

upper limit value, Ru, is shown, any number falling within the range specifically shown is. In particular, the following numbers within the range are specifically shown: R=R<L>+k<*>(R<u->R<L>), where k is a variable ranging from 1 percent to 100 percent with a 1 percent stepwise increase, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent 50

percent, 51 percent, 52 percent 95 percent, 96 percent, 97 percent, 98 percent, 99 percent or 100 percent. Also, any numerical range defined by two R numbers as defined above is also specifically shown.

Provided herein is a coated paper comprising a coating composition on at least one side of a base paper, wherein the coating composition comprises aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate, aluminum polyphosphate particles or combinations thereof. In certain embodiments, the coating compositions further include a solvent, an additive, and optionally one or more additional pigments.

The terms "aluminum phosphate" and "aluminum phosphate composition," as used herein, are intended to include aluminum phosphate as well as aluminum polyphosphate, aluminum orthophosphate, aluminum metaphosphate, and mixtures thereof.

The term "cavity" referred to herein is generally synonymous with the term "hollow particle," and is also described herein as a "closed cavity." The cavity (or closed cavity or hollow particle) is part of a core and shell structure of the aluminum phosphate mixture. The voids can be observed and/or characterized using either transmission or scanning electron microscopes ("TEMs" or "SEMs"). The use of TEMs or SEMs is well known to those skilled in the art. In general, optical microscopy is limited, by the wavelength of light, to resolutions in the range of a hundred, and usually hundreds, of nanometers. TEMs and SEMs do not have this limitation and are able to achieve a significantly higher resolution, in the range of a few nanometers. An optical microscope uses optical lenses to focus light waves by bending them, while an electron microscope uses electro-magnetic lenses to focus beams of electrons by bending them. Beams of electrons provide great advantages over beams of light both in the control of magnification levels and in the clarity of the image that can be produced. Scanning electron microscopes complement transmission electron microscopes in that they provide a tool to obtain the three-dimensional image of the surface of a sample.

Amorphous (ie, non-crystalline) solids exhibit differences from their crystalline counterparts of a similar composition, and such differences can confer advantageous properties. For example, such differences may include one or more of the following: (i) the non-crystalline solids do not diffract X-rays at sharply defined angles but may produce a broad scattering halo instead; (ii) the non-crystalline solids do not have well-defined stoichiometry, hence they can cover a wide range of chemical compositions; (iii) the variability of chemical composition includes the possibility of incorporation of ionic constituents other than aluminum and phosphate ions; (iv) since amorphous solids are thermodynamically metastable, they may show a tendency to undergo spontaneous morphological, chemical and structural changes; and (v) the chemical composition of the crystalline particle surface is highly uniform while the chemical composition of the surface of amorphous particles may show large or small differences, either suddenly or gradually. In addition, while particles of crystalline solids tend to grow by the well-known mechanism of Ostwald ripening, non-crystalline particles can expand or swell and shrink (de-swell) by water sorption and desorption, to form a gel-like or plastic material that is easily deformed when subjected to shearing, compression or capillary forces.

The aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and aluminum polyphosphate particles used in the coating compositions can generally be characterized by several different characteristics. For example, the aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and aluminum polyphosphate particles, when prepared in powder form, include particles where some of the particles have at least one void per particle, on average. Additionally, when the aluminum phosphate, polyphosphate and/or metaphosphate is in powder form, samples subjected to a differential scanning calorimetry test will show two distinct endothermic peaks, the peaks generally occurring between 90 "Celsius and 250 "Celsius. In certain embodiments, the first peak occurs approximately between temperatures of approximately 96° Celsius and 116° Celsius, and the second peaks occur approximately between temperatures of 149° Celsius and 189° Celsius. In other embodiments, the two peaks occur at about 106° Celsius and about 164° Celsius. In addition, the aluminum phosphate typically exhibits excellent dispersibility characteristics, as described herein.

In certain embodiments, the amorphous aluminum phosphate or polyphosphate for use in the coating compositions provided herein further comprises an ion, such as sodium, potassium or lithium ion. In one embodiment, the amorphous aluminum phosphate or polyphosphate further comprises sodium. In certain embodiments, the amorphous aluminum phosphate or polyphosphate is characterized by a bone density of between 1.95 and 2.50 grams per cubic centimeter. In certain embodiments, the amorphous aluminum phosphate or polyphosphate is characterized by a wood skeletal density of about 1.95, 2.00, 2.10, 2.20, 2.30, 2.40 or 2.50 grams per cubic centimeter. In certain embodiments, the amorphous aluminum phosphate or polyphosphate has a phosphorus to aluminum molar ratio of greater than 0.8 to 1.3.1 certain embodiments, the amorphous aluminum phosphate or polyphosphate has a phosphorus to aluminum molar ratio of greater than 0.9 to 1.3.1 certain embodiments embodiment, amorphous aluminum phosphate or polyphosphate has a phosphorus to aluminum molar ratio of about 0.8, 0.9, 1.0, 1.1, 1.2 or 1.3.1 certain embodiment, amorphous aluminum phosphate or polyphosphate has a sodium to aluminum molar ratio of about 0.6 to 1.4. In certain embodiments, amorphous aluminum phosphate or polyphosphate has a sodium to aluminum molar ratio of 0.6, 0.7, 0.76, 0.8, 0.9, 1, 0, 1, 1, 1, 2 or 1.3 .

In one embodiment, the aluminum phosphate or polyphosphate for use in the coating compositions is provided herein in a powder form and has, for example, one to four voids per particle of amorphous aluminum phosphate or polyphosphate powder. The amorphous aluminum phosphate or polyphosphate powder exhibits this tendency to form closed voids, or hollow particles, to an extent not previously observed for aluminum phosphates, polyphosphates or any other particles. In some embodiments, the aluminum phosphate, polyphosphate, or metaphosphate particles are substantially free of open pores while containing multiple closed pores. The powder form of the product may comprise an average individual particle radius size of between 10 and 80 or 20 and 80 nanometers. In one aspect, the powder form of the product may comprise an average individual particle radius size of between 10 to 70, 10 to 60, 10 to 50, 10 to 40, 10 and 30, or 10 and 20 nanometers. In one aspect, the powder form of the product may comprise an average individual particle radius size of between 20 to 70, 20 to 60, 20 to 50, 20 to 40, or 20 and 30 nanometers.

In certain embodiments, the particle size of aluminum phosphate particles is controlled to maximize light scattering. In certain embodiments, particle size determination is done by static light scattering in a Cilas model 1064 instrument. In certain embodiments, the amorphous aluminum phosphate or polyphosphate is characterized by a particle size distribution between about 0.1 to about 5 microns. In one embodiment, the amorphous aluminum phosphate or polyphosphate is characterized by a particle size distribution between about 0.2 to about 0.6 microns, about 0.6 to about 1.0 microns, about 1.0 to about 1.5 microns, about 1.0 to about 3.0 microns or about 1.60 to about 3.82 microns. In certain embodiments, the aluminum phosphate provided herein is micronized in a hammer mill to particle size within 3 microns (d 10) and 19 microns (d90). In one embodiment, particle size for highly diluted, sonicated samples is 0.1 micron, in a dynamic light scattering instrument (Brookhaven ZetaPlus).

In general, the amount of aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and/or aluminum polyphosphate pigment present in the coating compositions described herein can vary widely depending on the desired properties in the final coated paper product. In certain embodiments, the aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate, and/or aluminum polyphosphate pigment provided herein is used in the composition in an amount greater than about 1%, 3%, 5%, 7%, 10%, 12%, 15%, 20 %, 25%, 30%, 35%, 40% or 50% of the total weight of solids in the coating composition. In certain embodiments, the aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and/or aluminum polyphosphate pigment provided herein is used in the composition in an amount of from about 1% to about 45%, 3% to about 40%, 5% to 30%, 5% to 20% of the total weight of solids.

In certain embodiments, the coating compositions described herein are aqueous compositions. The compositions include water in an amount sufficient to provide the composition with desired flow properties. That is, the coating composition should be sufficiently flowable to allow it to be applied to a paper substrate and form a continuous coating on the paper substrate. In certain embodiments, water in the composition is in an amount greater than about 10%, 20%, 30%, 40%, 50%, or 60% by total weight of the composition. In certain embodiments, the water present in the composition is in an amount of between about 10% by weight and about 70% by weight, between about 20% by weight and about 60% by weight, between about 30% by weight and about 60% by weight %.

Without being bound by any particular theory, it is believed that the amorphous aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and/or aluminum polyphosphate pigment used in the coated papers provided herein is deformable so as to flow with the binder, such as latex, used in the composition , and takes the shape necessary to fill the holes in the paper coating which gives a smooth surface (shininess). It is further assumed that the pigment has absorbed surface water which is released during the thermal exposure and calendering (pressing) which exposes the strong binding nature of the surface to the latex.

The aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate, and/or aluminum polyphosphate pigment used in the coated paper and paper product provided herein may be prepared by methods known to those skilled in the art including methods described in U.S. Pub. No. 2006/045831 and U.S. Pub. No. 2006/0211798 and International Publication No. WO 2008/017135, all of which are hereby incorporated by reference in their entirety. For example, the U.S. pub. No. 2006/ 045831 and U.S. Pub. No. 2006/0211798 a method for the production of amorphous aluminum phosphate by combining phosphoric acid with aluminum sulfate and an alkaline material such as sodium hydroxide, while International Publication No. WO 2008/017135 shows a method for the production of amorphous aluminum phosphate using a different process; namely, one which involves combining the use of sodium aluminate. In one exemplary embodiment, the amorphous aluminum phosphate is prepared using a two-step process of combining phosphoric acid and aluminum hydroxide to give an acidic aluminum phosphate solution or suspension, and then neutralizing the solution or suspension by the addition of sodium aluminate. In another exemplary embodiment, the amorphous aluminum phosphate is produced by reacting phosphoric acid, aluminum hydroxide and sodium aluminate in a single step.

RAW PAPER

Suitable base papers for making the coated paper include, a thin paper, a kraft paper, a quality paper, cotton fiber paper, a baryte paper, recycled and unbleached paperboard and bleached paperboard, and wet batch paper fiber pulp or wet batch paper sheet, including natural cellulosic, recycled or synthetic fiber pulp or sheet shaped from there. The term "paper laminate" means paper comprising two or more paper layers or thin layers.

The base paper can be produced from suitable components known to a person skilled in the art, for example, chemical fiber pulps, such as, kraft pulp (KP), sulphite pulp, mechanical pulps, for example, stone ground pulp (SGP), refiner ground pulp (RGP), thermomechanical pulp, chemical thermomechanical pulp and bleached chemical thermomechanical pulp, waste paper pulps, for example, de-inking pulps, and non-wood pulps, for example, bagasse, esparto, kenaf, bamboo, straw, flax and jute pulps. The fiber masses can also be used in combination with at least one element selected from synthetic organic fibers, for example, polyamide and polyester fibers, regenerated fibers, for example, polynosic fibers and inorganic fibers, for example, glass, ceramic and carbon fibers. In certain embodiments, chlorine-free fiber pulps, such as ECF (elemental chlorine-free) fiber pulp and TCF (total chlorine-free) fiber pulp, are used as the fiber pulp to form the base paper.

ADDITIVES

The aluminum phosphate compositions used in the coated papers provided herein may include one or more conventional additives to improve the performance of the composition. Suitable additives can, for example, be selected from binders, lubricants, dispersants, leveling agents, antifoams, wetting agents, optical brighteners, biocides, crosslinking agents, water retention agents, viscosity modifiers or thickeners and combinations thereof. Various components used in the compositions are described in Lehtinen, Esa, Pigment Coating and Surface Sizing of Paper, Helsinki: Fapet Oy, 2000. The entire disclosure in this publication is incorporated herein by reference.

In certain of the coating compositions provided herein, the present additives are included in the compositions as "parts per hundred parts of aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and/or aluminum polyphosphate pigment"; that is, the amounts of binder and various other additives are referenced against the amount of pigment present. In certain embodiments, the reference to parts per hundred is to the total amount of all pigments in the formulation, including the aluminum phosphate pigment. The amount of binder present in the compositions described herein can vary greatly depending on the desired properties in the final paper product. A person skilled in the art can determine a suitable amount of binder for a desired application based on the knowledge available in the art and explanation herein.

Binders

In one embodiment, the compositions provided herein further comprise a binder or an adhesive. The binder improves the properties of the coated paper both during the coating process and after the coating process, when printing processes are carried out. Specifically, during the coating process, the binder provides cohesion of all coating components in the dried coating and adhesion of the coating to the paper tap. Furthermore, the binder, together with water, serves as a carrier for the pigment and affects the rheological behavior and water retention of the composition during the coating procedure. In certain embodiments, the binder is present in an amount of from about 1 part (per hundred parts pigment) to about 30 parts (per hundred parts pigment), in another embodiment, from about 5 parts (per hundred parts pigment) to about 25 parts (per hundred parts pigment).

Suitable binders for use in the compositions provided herein include, for example, proteins, starches, gums, resins, emulsion polymers such as latexes, casein, polyvinyl alcohol, and combinations thereof. Suitable proteins for use as a binder in the composition include soy proteins and casein. Suitable starches for use as a binder in the composition include corn starch, tapioca, white potato, sorghum, waxy corn, waxy sorghum, sweet potato, rice and

wheat starch. Suitable latex emulsion polymers include styrene butadiene rubber, styrene acrylate, styrene acrylonitrile, vinyl acrylate, acrylic, polyvinyl acetate and combina-

tions thereof. Another suitable binder is biopolymer nanoparticle latex made from starch as described in US Patent 6,825,252.

The resins for compositions include monomers or polymers or combinations thereof that are compatible with the coating and end use. Suitable resins include, but are not limited to, polyester, polyurethane, polyacrylic resins, polyester-epoxy resins, or combinations thereof. Suitable polyester resins can be obtained, for example, by polymerization-condensation reaction between a polybasic saturated acid or an anhydride thereof and a polyalcohol. Examples of epoxy resins include, but are not limited to, bisphenol-A resins, novolak epoxy resins, cyclic epoxy resins, or combinations thereof. In certain embodiments, acrylic resins can be obtained by copolymerizing functional monomers such as acrylic acid and various copolymerizable monomers such as, for example, unsaturated olefinic monomers such as ethylene, propylene and isobutylene, aromatic monomers such as styrene, vinyltoluene, alpha-methyl styrene, esters of acrylic and methacrylic acid with alcohols having from 1 to 18 carbon atoms, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, lauryl acrylate, lauryl methacrylate, vinyl esters of carboxylic acids having 2 to 11 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl 2-ethylhexyl acrylate or other co-monomers such as vinyl chloride, acrylonitrile and methacrylonitrile. Some examples of polyurethane resins include, but are not limited to, blocked urethane polymers obtained by polycondensation of isocyanates with various polyols.

In one embodiment, resins include acrylic resin containing at least one hydroxyl group and one epoxy group per molecule. Such acrylic resins can be obtained, for example, by copolymerization of a hydroxyl-containing polymerizable monomer, epoxy-containing polymerizable monomer, acrylic polymerizable monomer, and if necessary even other polymerizable monomer(s). A hydroxyl-containing polymerizable monomer is a compound containing at least one hydroxyl group and polymerizable double bond per molecule, examples of which include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxy-butyl methacrylate or hydroxyalkyl (meth)acrylates which are obtained by to react the preceding with lactones. An epoxy-containing polymerizable monomer is a compound containing at least one each of epoxy group and polymerizable double bond per molecule, examples of which include glycidyl acrylate, glycidyl methacrylate and allyl glycidyl ether. Acrylic polymerizable monomers include mono-esterified products of acrylic acid or methacrylic acid with C1-C20 monoalcohols, specific examples include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate tacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate and cyczxzselo-hexyl methacrylate. Moreover, C2-C20 alkoxyalkyl esters of acrylic acid or methacrylic acid can also be used as the acrylic polymerizable monomers.

Lubricants

The lubricants for use in the compositions include polyoxyalkylene mono- or diesters or mixtures thereof of phosphoric acid, or a polyoxyalkylene mono- or diester or mixtures thereof of phosphoric acid salts, fatty acids, alkali metal salt of fatty acids, or alkaline earth metal salt of fatty acids, sulphonated oils, amines, calcium or ammonium stearates, ureas, ethoxylated glycerol, ethoxylated propoxylated glycerol, letcitinoleate and suitable emulsifiers. In one embodiment, the lubricant is present in an amount up to about 2%, 1.5% or 1% by weight of the aluminum phosphate, aluminum metaphosphate, aluminum otrophosphate and/or aluminum polyphosphate pigment.

Dispersants

The dispersants for use herein comprise a salt and/or ester of: (i) an amine, alcohol and/or alkanolamine and (ii) an inorganic and/or organic polyprotic acid, wherein the molar ratio of the amine, alcohol and/or alkanolamine to the polyprotic -protic acid is greater than 3:1.1 various embodiments, the molar ratio of amine, alcohol and/or alkanolamine to polyprotic acid is 4:1 to about 20:1. This molar ratio allows the production of pigments that have improved stability, hiding power, color refraction strength and/or gloss.

One or more amines, alcohols and/or alkanolamines suitable for use in the manufacture of the dispersant include, but are not limited to, amino alcohols, diols, triols, amino polyols, polyols, primary amines, secondary amines, tertiary amines, quaternary amines or a combination thereof. In one embodiment, the amines and/or alcohols include, but are not limited to, triethylamine, diethylamine, ethylenediamine, diethanolamine, triethanolamine, 2-amino-2-methyl-1-propanol, 1-amino-1-butanol, 1 -amino-2-propanol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-hydroxymethyl-1,3-propanediol, methanol , isopropyl alcohol, butanol, methoxypropanol, trimethylolethane, trimethylolpropane, pentaerythritol, ethylene glycol, propylene glycol or a combination thereof.

The one or more polyprotic acid(s) suitable for use in the manufacture of the dispersant include, but are not limited to, phosphoric acid, polyphosphoric acid, phosphonic acid, phosphinic acid, metaphosphoric acid, pyrophosphoric acid, hypophosphoric acid, phosphorus (III) pentaoxide , other phosphoric acid derivatives or derivatives of any phosphorous (111)-containing acid or combinations thereof.

In one embodiment, the dispersant for use in the coating compositions herein is sodium polyacrylate.

In various embodiments, the dispersant, when added to a pigment, provides viscosity stability and resistance to flocculation for the pigment. Typically, the dispersant is present in the composition in weight percentages of up to about 5% based on the weight of the aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and/or aluminum polyphosphate pigment. In one embodiment, the dispersant is present in amounts of from about 0.01 to about 3%, 0.01 to about 2%, or 0.01 to about 1%, based on the weight of aluminum phosphate, aluminum metaphosphate, aluminum otrophosphate and/or the aluminum polyphosphate pigment.

Mixing of the dispersant with the aluminum phosphate, aluminum metaphosphate, aluminum otrophosphate and/or aluminum polyphosphate pigment can be carried out by mixing methods known in the art. Accordingly, the mixing can be carried out, for example, with a blender or any other high-speed mixing device. Blade speeds of 50 rpm or higher, for example 1000 rpm to 3000 rpm, are generally used for mixing.

Antifoam agents

The antifoam agents for use in the compositions include, but are not limited to, mixtures of surfactants, tributyl phosphate, fatty polyoxyethylene esters plus fatty alcohols, fatty acid soaps, silicone emulsions and other silicone-containing compositions, waxes and inorganic particles in mineral oil, vegetable oils, mixtures of emulsified hydrocarbons and others compounds sold commercially to perform this function. Such defoamers/antifoam agents can be used in amounts up to about 1% by weight.

Cross-linking agents

The crosslinking agents for use include, for example, glyoxals, glyoxalated resins, melamine-formaldehyde resins, and ammonium-zirconium carbonates. in one embodiment, the cross-linking agent is present in an amount up to about 5%, 4%, 3%, 2% or 1% by weight of the aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and/or aluminum polyphosphate pigment.

Water retention agents

The water retention agents for use herein include, for example, sodium carboxymethyl cellulose, hydroxyethyl cellulose, PVOH (polyvinyl alcohol), starches, proteins, polyacrylates, gums, alginates, polyacrylamide bentonite and other commercially available products sold for such applications. In one embodiment, the water retention agent is present in an amount up to about 2%, 1.5% or 1% by weight of the aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and/or aluminum polyphosphate pigment.

Viscosity modifiers

The viscosity modifiers and/or thickeners for use herein include, for example, acrylic associative thickeners, polyacrylates, emulsion copolymers, dicyanamide, triols, polyoxyethylene ether, urea, sulfated castor oil, polyvinylpyrrolidone, CMC (carboxymethylcelluloses, such as sodium carboxymethylcellulose), sodium alginate , xanthan gum, sodium silicate, acrylic "add" copolymers, HMC (hydroxymethyl celluloses), HEC (hydroxyethyl celluloses) and others. In one embodiment, the viscosity modifiers and/or thickeners may be used in amounts up to about 2%, 1.5%, or 1% by weight of the aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate, and/or aluminum polyphosphate pigment.

Dry or wet picking enhancement additives

In certain embodiments, the compositions comprise one or more dry or wet picking enhancement additives. Such additives may be used in amounts up to about 2% by weight, and include, for example, melamine resin, polyethylene emulsions, urea formaldehyde, melamine formaldehyde, polyamide, calcium stearate, styrene maleic anhydride and others.

Dry or wet "rub" improvement and/or wear resistance additives

In certain embodiments, the compositions comprise one or more dry or wet "rub" improvement and/or wear resistance additives. Such additives may be used in amounts up to about 2% by weight, and include, for example, glyoxal-based resins, oxidized polyethylenes, melamine resins, urea formaldehyde, melamine formaldehyde, polyethylene wax, calcium stearate and others.

Gloss-ink opacity additives

In certain embodiments, the compositions comprise one or more gloss-ink opacity additives. Such additives may be used in amounts up to about 2% by weight, and include, for example, oxidized polyethylenes, polyethylene emulsions, waxes, casein, guar gum, CMC, HMC, calcium stearate, ammonium stearate, sodium alginate and others.

Optical whitening agents

In certain embodiments, the compositions comprise one or more optical brighteners (OBA) and/or fluorescent brighteners (FWA). Such agents may be used in amounts up to about 1% by weight, and include, for example, stilbene derivatives. In certain embodiments, PVOH is used as an OBA carrier to improve the performance of stilbene OBA.

Biocides/rotting control agents

In certain embodiments, the compositions comprise one or more biocides/rot control agents. Such agents may be used in amounts up to about 1% by weight, and include, for example, metaborate, sodium dodecylbenzene sulfonate, thiocyanate, organosulfur, sodium benzoate and other compounds sold commercially for this function, e.g., the line of biocides sold at Nalco.

Planning and leveling aids

In certain embodiments, the compositions comprise one or more planning and leveling aids. Such auxiliaries may be used in amounts up to about 2% by weight, and include, for example, non-ionic polyol, polyethylene emulsions, fatty acid, esters and alcohol derivatives, alcohol/ethylene oxide, sodium CMC (carboxymethyl cellulose), HEC (hydroxyethyl cellulose), alginates, calcium stearate and other compounds sold commercially for this function.

Grease and oil resistance additives

In certain embodiments, the compositions comprise one or more grease and oil resistance additives. Such additives may be used in amounts up to about 2% by weight, and include, for example, oxidized polyethylenes, latex, SMA (styrene maleic anhydride), polyamide, waxes, alginate, protein, CMC (carboxymethyl cellulose), HMC (hydroxyethyl cellulose) and fluorocarbons.

Water resistance additives

In certain embodiments, the compositions comprise one or more water resistance additives. Such additives may be used in amounts up to about 2% by weight, and include, for example, oxidized polyethylenes, ketone resins, anionic latex, polyurethane, SMA, glyoxal, melamine resin, polyamide, glyoxals, stearates and other materials commercially available for this function .

In certain embodiments, the compositions comprise one or more dyes, which may be used in amounts up to about 0.5% by weight.

Additional pigments

In certain embodiments, the compositions provided herein further include one or more additional pigments, such as calcium carbonate, including ground calcium carbonate (GCC), calcined kaolin, hydrous kaolin, delaminated clay, kaolin clay, porcelain earth, talc, mica, dolomite, silica, silicates, zeolite , gypsum, satin white, titanium oxide, titanium dioxide, calcium sulfate, barium sulfate, aluminum trihydrate, plastic pigment and combinations thereof.

In certain embodiments, the compositions comprise one or more dyes or colored pigments, which may be used in amounts up to about 0.5% by weight.

In certain embodiments, the compositions comprise a combination of

aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and/or aluminum polyphosphate pigment and GCC pigments. In certain embodiments, the compositions comprise a combination of aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and/or aluminum polyphosphate pigment and titanium dioxide pigments. In one embodiment, the amount of titanium dioxide pigment is about 1%, 3%, 5%, 7%, 10%, 15%, 20%, 25%, 30%, 35%, 50% or more of the total weight of solids in the composition . In another embodiment, the ratio of aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and/or aluminum polyphosphate pigment and titanium dioxide pigment in the compositions is about 1:1,1,5:1, 2:1, 2,5:1, 3:1, 3 ,5:1 or 4:1.1 another embodiment, the ratio of titanium dioxide pigment and aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and/or aluminum polyphosphate pigment in the compositions is about 1:1,1,5:1, 2:1, 2.5: 1, 3:1, 3.5:1 or 4:1.

In one embodiment, the amount of aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and/or aluminum polyphosphate pigment in the compositions is at least about 1%, 3%, 5%, 7%, 10%, 12%, 20%, 25%, 30%, 40%, 50%, 60% or 70% and the amount of GCC pigment is about 5%, 10%, 20%, 30%, 40%, 50%, 60% or 70% of the total weight of solids in the composition. In one embodiment, the amount of aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and/or aluminum polyphosphate pigment in the compositions is at least about 1%, 3%, 5%, 7%, 10%, 12%, 20%, 25%, 30%, 40%, 50%, 60% or 70% and the total amount of one or more other pigments about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70% or 80% of the total weight of solids substances in the composition.

In certain embodiments, the combination of aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and/or aluminum polyphosphate pigment and titanium dioxide pigment increases both gloss and opacity of the coated paper.

Any of the additives and additive types above can be used alone or in combination with each other and/or with other additives, if desired.

The total solids content of the compositions provided herein is typically at least about 50% by weight solids, in certain embodiments at least about 60%, in certain embodiments at least about 70%, and as high as considered suitable by a person skilled in the art but still providing a suitable liquid composition which can be used in coating. In certain embodiments, the total solids content of the compositions is about 55%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 72% , 75% or 80%.

PREPARATION OF THE COATING COMPOSITIONS

According to another aspect, provided herein is a process for preparing the aluminum phosphate compositions for coating a paper, this process comprising mixing the aluminum phosphate, aluminum metaphosphate, aluminum orthophosphate and/or aluminum polyphosphate pigment, a binder and any other optional additional ingredients in an aqueous liquid medium to produce a suspension of the solid components therein. The composition may conveniently be prepared by conventional compounding techniques, which will be well known to one skilled in the art.

PAPER COATING PROCESS

According to another aspect, there is provided herein a method of making a coated paper, which comprises applying the composition for coating a base paper, drying the coating and calendering the paper to form a coated paper surface, e.g. a gloss coating, at that. The coating can be formed on both sides of the paper.

In the calendering step, paper smoothness and gloss are improved and bulk is reduced by passing a coated paper sheet between calender nips or rollers one or more times. Typically, elastomeric coated rollers are used to provide leveling and smooth rolling of the coated paper surface. In certain embodiments, an elevated temperature is applied. One or more (eg up to about 12, or sometimes higher) passes through the nips may be performed.

Methods for coating paper and other sheet materials, and apparatus for carrying out the methods, are widely published and well known. Such known methods and apparatus can suitably be used for the production of coated paper provided herein. For example, a review of such methods published in Pulp & Paper International, May 1994, pages 18 et seq, is incorporated in its entirety by reference. (This is a badly dated and incomplete reference.)

Paper sheets may be coated inline on the paper machine, ie, "on-machine," or "off-machine" on a coater or coater. The use of compositions with a high content of solids is desirable in the coating method because it leaves less water which must then evaporate. However, as is well known in the art, the level of solids should not be so high that high viscosity and planing problems are introduced.

The methods of coating may be carried out using apparatus comprising (i) an applicator for applying the coating composition to the paper to be coated; and (ii) a measuring device to ensure that a correct level of coating composition is applied. When an excess of coating composition is applied to the applicator, the metering device is downstream of it. Alternatively, the correct amount of coating composition may be applied to the applicator by the metering device, e.g. like a film press. At the points of coating application and measurement, the paper web support spans from a support roll, e.g. via one or two applicators, to nothing (ie just tightening). The time the coating is in contact with the paper before the excess is finally removed is the holding time - and this can be short, long or variable.

The coating layer can be formed on both the front and back surfaces of the raw paper and/or in a multilayer structure. The multi-layer coating layer can be formed by forming one or more intermediate coating layers on a base paper surface, and an outermost coating layer is formed on the intermediate coating layer or layers. When the coating layer is formed on the two surfaces of the raw paper or in the multilayer structure, the coating compositions and the amount of several of the coating layers may be the same as each other or different from each other. The composition of each coating liquid can be designed with regard to the purpose and the desired properties of the coating layer. When the coating layer is formed on only a front surface of the base paper, the back surface of the base paper may be coated with a synthetic resin layer, a pigment-binder compound layer, or an anti-static layer. The back coating layer mentioned above helps to improve a resistance to curling, printability and a resistance to blocking the supply and/or delivery of the coated paper into or from the printer. The back surface of the base paper may be treated with an adhesive, a magnetic material, a flame retardant, a heat resistance agent, a waterproofing agent, an oil sealing agent or an anti-slip agent to provide a desired function to the back surface of the coated paper.

The compositions provided herein may be applied to one or more sides of the base paper by any method known in the art. For example, paper coating methods include, but are not limited to, roller applicator and dispensing by roller, wand, blade, pusher, air knife; "pond" applicator and dosing by roll, stick, blade, pusher or air knife; "fountain" applicator and dosing roller with roller, rod, blade, pusher or air knife; pre-dosed films or patterns, such as "gate" roll, three-roll, ani-lox, gravure, film press, curtain, spray; and foam application. In one embodiment, the paper product is fed through a rolling nip in which one of the rolls has previously been coated with the composition. The composition is transferred to the surface of the paper product. The excess composition is removed from the surface of the paper product using a steel float knife which forms a level coating profile on the surface of the sheet with the desired final coating weight to be applied.

In certain embodiments, the composition is applied to the paper product in an amount of from about 1 g/m<2> to about 30 g/m<2>. In other embodiments, the composition is applied to the paper product in an amount of from about 3 g/ m<2>to about 25 g/m<2>or from about 5 g/m<2>to about 20 g/m<2>.

THE COATED PAPER

The coated paper provided herein is suitable for several printing applications such as Giclee printing, color copying, xerography, screen printing, gravure, sublimation technique, flexography, inkjet printing, roll offset printing, electrophotographic printing, image registration paper for thermal transfer registration, inkjet registration, etc.

In one aspect, provided herein are inkjet papers and papers for digital printing comprising the aluminum phosphate compositions.

In another aspect, there is provided herein a coated coverboard for direct post press flexography to prevent rubbing and to improve image fidelity comprising the aluminum phosphate compositions.

In another aspect, there is provided herein an ultralight weight coated publication paper.

It is yet another aspect, provided herein is gravure printing paper comprising the aluminum phosphate compositions.

In certain embodiments, the coated paper herein has provided a coating gloss equal to or greater than about 10% at 75° as measured by TAPPI test method T480 om-92. This method measures the reflective gloss of the paper at 75<0> from the plane of the paper. In other embodiments, the coated paper provided herein has a coating gloss equal to or greater than about 20%, 30%, 40%, 50%, 55%, 60%, 65%, 70%, 75%, 80% at 75°. In one embodiment, the coating gloss at 75° is from about 25% to about 75%. In another embodiment, the coating gloss is from about 30% to about 65% at 80°.

In certain embodiments, the coated paper herein provides a smoothness of less than 5.0, 4.0, or 3.0 as measured using the TAPPI test method for Parker Print Surface: T555 om-99.1 one embodiment, the coated paper has Parker Print Surface from about 1.0 to about 2.5, from about 0.90 to about 2.25 or from about 0.90 to about 2.0.

In certain embodiments, the coated paper has an opacity greater than 80% as measured using TAPPI Test Method T425 om-91.1 In one embodiment, the coated paper has an opacity of from about 80% to about 99%. In another embodiment, the opacity is from about 85% to about 99%, about 90% to about 99%, about 92% to about 99%, or about 94% to about 99%.

In certain embodiments, the whiteness of the coated paper is greater than about 70%, 73%, 75%, 77%, 80%, 85% or 90% GE whiteness as measured using TAPPI test method T452 in 92.1 one embodiment, it has coated paper whiteness degree from about 70% whiteness degree to about 95% GE whiteness degree as measured using TAPPI test method T452 if 92.1 another embodiment, the whiteness degree is from about 80% whiteness degree to about 99% GE whiteness degree, or from about 85% whiteness degree to about 99% GE degree of whiteness.

In one aspect, the aluminum phosphate compositions used in the coated paper provided herein have improved rheology compared to silica and/or other specialty pigments. In certain embodiments, the aluminum phosphate compositions improve coating flowability and/or improve energy consumption during drying. In other embodiments, the aluminum phosphate compositions are in the form of aqueous slurries with a higher percentage of solids and good shear thinning rheology compared to existing compositions. Accordingly, the aluminum phosphate compositions provided herein result in faster on-machine drying rates due to coatings with a higher percentage of solids than existing compositions resulting in lower drying costs and reduced pressure rub.

In certain embodiments, the aluminum phosphate compositions have improved on-machine coating flowability and therefore improved production rates over existing compositions. In other embodiments, the aluminum phosphate compositions have low Einlehner wear resulting in reduced wear to process equipment and no metallic marks being left on the paper at the gripper bars.

In one embodiment, the aluminum phosphate compositions herein comprise compositions with higher solids content compared to existing compositions. In another embodiment, the aluminum phosphate compositions herein provide a low bulk density.

In another embodiment, the aluminum phosphate compositions provided herein coat paper with substantially no dusting, have improved optical/reflective densities of four-color cyan, magenta, yellow, black (CMYK) inkjet printing.

In yet another embodiment, the aluminum phosphate compositions provided herein enable lighter coating weights due to internal void volume.

In certain embodiments, the aluminum phosphate compositions provided herein have improved ink jet printing density, improved ink receptivity in printing papers and/or improved opacity.

In one embodiment, the aluminum phosphate compositions herein provide less pick-up and reduced roughening of the base sheet during application, resulting in a more evenly coated sheet.

In another embodiment, the aluminum phosphate compositions provided herein allow higher operating speeds and higher production rates. In yet another embodiment, the aluminum phosphate compositions herein have provided the ability to coat on high speed paper machines rather than only on low speed off-machine coating lines reducing waste and cost.

In one embodiment, the aluminum phosphate compositions provided herein can act as fillers in newsprint to prevent penetration, and as fillers in technical specialty papers such as corrosion protection, gas filtration, filter and absorbent papers.

In another embodiment, the aluminum phosphate compositions provided herein are used as microparticle retention aids, deinking aids in combination with flotation washing systems, or coefficient of friction (COF) control aids in recycled tire carton. Figures 1 and 2 provide comparison of low shear and high viscosities at 100 RPM for coating compositions comprising aluminum phosphate pigments and titanium dioxide pigments respectively. Figures 3 and 4 provide low shear and high viscosities at 100 RPM for coating formulations obtained by gradual replacement of TIO2 with aluminum phosphate pigments, respectively. As seen from Figures 1-4, addition of aluminum phosphate pigment increases both low-shear and high-shear viscosity. Figure 5 provides a comparison of water retention properties for coating compositions comprising aluminum phosphate pigments and titanium dioxide pigments. Figure 6 provides the effect on water retention for the coating compositions by replacing TiO 2 with aluminum phosphate. As can be seen, addition of aluminum phosphate had little effect on water retention. Figures 7 and 8 provide comparison of opacity for paper coated with compositions comprising aluminum phosphate pigments and titanium dioxide pigments respectively before and after calendering. Figure 9 provides an effect of replacing TIO2 with aluminum phosphate pigments on coated paper opacity. As can be seen, aluminum phosphate has the same opacifying ability as TiO 2 if not calendered. However, opacifying ability is reduced with calendering. Figure 10 provides a comparison of whiteness for paper coated with compositions comprising aluminum phosphate pigments and titanium dioxide pigments before and after calendering. Figure 11 provides an effect of replacing TiO 2 with aluminum phosphate pigments on whiteness of coated paper. As can be seen, aluminum phosphate is equal to or slightly better than Ti02i OBA performance. Figure 12 provides a comparison of gloss of paper coated with compositions comprising aluminum phosphate pigments and titanium dioxide pigments. Figure 13 provides an effect of replacing TiO 2 with aluminum phosphate pigments on the gloss of coated paper. As can be seen, aluminum phosphate is an excellent gloss pigment and gloss increases with the amount of aluminum phosphate. Accordingly, in certain embodiments, mixing aluminum phosphate with TiO 2 appears to increase both gloss and opacity. Figure 14 provides a comparison of surface strength of paper coated with compositions comprising aluminum phosphate pigments and titanium dioxide pigments. Figure 15 provides an effect of replacing TiO 2 with aluminum phosphate pigments on surface strength of coated paper. Figure 16 provides a comparison of surface coverage for compositions comprising aluminum phosphate pigments and titanium dioxide pigments. In certain embodiments, the use of aluminum phosphate has no significant effect on surface coverage.

COATED PAPER WITH HIGH BULK

In one embodiment, there is provided herein a high bulk coated paper which proportionally uses more base stock and less coating composition than similar grades of conventional paper of the same overall weight.

For example, while a conventional 30 pound per ream paper, where one ream is 3300 square feet of paper, may have the following properties:

In one embodiment, the paper has provided herein:

For a heavier paper of 32 Ibs./rm the data is:

The thickness of the papers above is as follows:

In certain embodiments, the high bulk coated paper provided herein may be manufactured as described in US Patent No. 6,254,725, by starting with a waterborne papermaking material having a high percentage of mechanical pulp, generally in excess of 50%, usually in the 55 to 75% range or around 65%. As used herein, the term common grinding stock may include stone grinding stock (SGW), pressure grinding stock (PGW) and chemical stock (CGW). mechanical refiner stock (RMP), thermomechanical stock (TMP) and chemical thermomechanical stock (CTMP). Exemplary sample formulations of pulp composition are: (1) 45% TMP/20

% SGW/35% Softwood Power (SWK); (2) 50% TMP/25% PGW/25% SWK and (3) 70-85% CTMP/30-15% SWK.

The pulp composition is used in a papermaking apparatus or machine that has a "gap former" instead of a conventional plane wire as described in US Patent No. 6,254,725. The inherent ability of the former "gap" to reduce the two-sidedness of the paper base allows to achieve the minimum coating application with good gloss.

The above manufactured paper then moves into the press section where it can be conventionally pressed. The press section may include a wide slide piece or extended "nip press" which is believed to compress the paper tap less than conventional, resulting in the paper tap retaining more bulk and/or thickness. The extended nip press preserves bulk but still allows water removal from the paper tap due to the extended time the paper tap is in the nip, which allows the use of a lower than conventional nip pressure. The paper web is then passed through the dryer section and dried to a moisture content of less than 10%, or to 5% or less. The paper can then be coated with the coating compositions comprising aluminum phosphate on or off the papermaking machine.

As noted above, the coating weight applied to the paper tap is less than conventional, but due to the smoothness and uniformity of the paper base formed in the "gap", the paper base can be coated acceptably with a smaller amount of coatings, resulting in high bulk and allows a paper of a given weight to proportionately comprise a greater percentage of paper base and a smaller percentage of coating than is conventional. The amount of aluminum phosphate pigment used can be regulated to achieve the desired bulk and gloss. The coating can be applied to one or both sides of the paper tap. The compositions may further contain a plastic pigment and additives as described elsewhere herein.

In general, the coating may be applied with any conventional type of sheet coater and such as a short dwell time applicator as shown in U.S. Pat. Pat. Nos. 4,250,211 and 4,512,279, and/or a "fountain" type coater shown in U.S. Pat. Pat. No. 5,436,030 and/or a double blade coater as shown in U.S. Pat. Pat. No. 5,112,653, what is shown in those patents is incorporated herein by reference. In addition, the coating may be applied by a film coater or Speedcoater applicator manufactured by Voith Sulzer GmbH, as shown in U.S. Pat. Pat. No. 4,848,268. Other suitable types of dosing, such as with a ductor rod, grooved or smooth, could also be used.

The coated paper can then be calendered, hot-soft calendered and/or super calendered.

In one embodiment, provided herein is a high bulk coated paper comprising a base paper having a weight of 18 to 34 pounds per board and a coating composition on at least one side of the base paper, wherein the composition comprises an amorphous aluminum phosphate or polyphosphate pigment, and the coating composition has a weight of not more than about 2 or 3 pounds per rice per page, and the base paper has a thickness of at least about 80, 85, or 88% of the total thickness of the coated paper and the coating composition provides substantially the remainder of the thickness of the coated paper , so that the coated paper has a bulk factor of at least 55.

In another embodiment, provided herein is a light weight, high bulk coated paper comprising a base paper having a weight of about 26 to 36 pounds per pad, and a coating composition on at least one side of the base paper, wherein the composition comprises an amorphous aluminum phosphate- or polyphosphate pigment, and the coating composition has a weight of not more than about 3 pounds or is about 1.5 to 3.5 pounds per rice per side, and the base weight and coating weight are selected such that the base has a thickness of at least about 75, 80 , 85 or 88% of the total thickness of the coated paper and the coating composition provides substantially the remainder of the thickness of the coated paper such that the coated paper has a bulk factor of at least 55.

In yet another embodiment, there is provided herein an ultralight weight, high bulk coated paper comprising a base paper base having a weight on the order of about 18 to 24 pounds per pad, and a coating composition on at least one side of the base paper, wherein the composition comprises an amorphous aluminum phosphate or polyphosphate pigment and the coating composition has a weight of about 2 pounds per rice per side, and the base weight and coating weight are selected such that the base has a thickness of at least about 75, 80, 85 or 88% of the total thickness of the coated the paper and coating composition provide substantially the remainder of the thickness of the coated paper such that the coated paper has a bulk factor of at least 55.

In certain embodiments, the coating composition is applied in substantially equal weights to each side of the base paper. In certain embodiments, the coated paper has a bulk factor of at least 50, 52, 55, 58, 60 or more. The bulk factor can be calculated as described in US Patent No. 6,254,725. In certain embodiments, the coated paper has a 75<0>TAPPI gloss of 30, 35, 40 or above.

In certain embodiments, the resulting coated paper has one or more of the following characteristics compared to conventional coated paper of the same weight: 10-20% fewer linear feet/roll of paper for the same roll diameter, evidencing the higher bulk of the paper; less weight per roll because of the same roll diameter; about 10-20% higher thickness; about 10-15% higher stiffness; around 0.5-1.0 pt. or more increase in opacity and degree of whiteness; and print smoothness and gloss equivalent to conventional paper.

The high bulk, light weight coated paper provided herein is desirable for use in magazines requiring very low basis weight to reduce paper costs by increasing printing area per ton of paper and by reducing postage cost per magazine. High bulk paper will improve the economics of magazine publishing by allowing a lower basis weight to be substituted for a higher basis weight of conventional quality.

The increased stiffness of the paper also improves paper web stiffness for low basis weight paper resulting in better flowability on high speed printing presses and folding machines used to produce magazines. The thicker paper also provides a bulkier magazine that is less fragile when handled. A bulkier magazine "feels more solid" i.e. it won't sag or feel limp. Individual pages will come apart more easily and turn without sticking together

Certain examples of coating formulations are described below. The following examples are presented to exemplify embodiments of the compositions. All numerical values are approximate. When numerical ranges are given, it should be understood that embodiments outside the stated ranges may still fall within the scope of the invention. Specific details described in each example should not be considered necessary characteristics of the invention.

EXAMPLES

EXAMPLE 1: Comparison of aluminum phosphate pigment with plastic pigment

Coatings were prepared according to Table 1. The GCC (ground calcium carbonate),

Hydrocarb 90, was dispersed at 72% solids with a high shear Cowles dispersing unit. No. 1 the clay pigment, Hydrafin, was dispersed at 70% solids. Aluminum phosphate pigment at 34.2% solids was dispersed with the high shear Cowles dispersing unit prior to use. After the pigments were dispersed, the other coating components were added under gentle stirring with a mixer in the order listed in Table 1. After combining all the coating components, the solids content of the coating was adjusted with dilution water in an attempt to achieve the same targets solids content, Table 2. The solids in the coating and Brookfield viscosity were measured. Brookfield viscosities were measured using a #5 spindle at 100 RPM, 23°C, also in Table 2. The coatings were also tested on a Hercules high shear rheometer with a than E bob/20.4 sec rise time.

Coatings were applied to an uncoated 153.5 gsm free sheet (dried) at 3800 fpm on a cylindrical laboratory coater (CLC). The base paper had the following characteristics: basis weight: 153.5 gsm (dried) and 165.0 gsm (air dry-7% moisture); smoothness: 5.98 microns ± 0.19; degree of whiteness: 90.07% ± 0.15. The CLC was set up using a 0.020 inch coating blade, 0.025 inch backing blade and 0.375 inch extension. A coating weight of 10 gsm was targeted. After coating, samples were cut to test size and conditioned to TAPPI standards. After conditioning, the optical properties (gloss, whiteness and L<*>, a<*>, b<*>color) and smoothness were measured according to TAPPI standard test methods. Smoothness was measured using a Parker Print Surface tester. The samples were then calendered through 2 nips against the steel roll at 150°F and 160°F and 600 and 1200 pli. Temperatures were not increased above 160°F to prevent blocking problems (sticking to the metal roll). The results in Figure 17 show an increase in gloss with a 5 part replacement of GCC with aluminum phosphate pigment. A higher increase in gloss was observed with the replacement of 5 parts GCC with plastic pigment. A comparison of coating 3 with coating 4 indicates that 10 parts aluminum phosphate pigment coating had a comparable gloss to the coating with 5 parts plastic pigment. It should be noted that the coating of 10 parts plastic pigment was made on an actual basis of dry pigment solids of 25%. Plastic pigment is sold on an effective solids basis of 50%. Accordingly, on an effective solids basis one would compare coatings 3 and 4. This comparison shows that the gloss of the aluminum phosphate pigment coating is comparable to the plastic pigment coating. The small differences can be attributed to differences in the calendering response of the two pigments. The plastic pigment responded better to calendering temperature than aluminum phosphate pigment. The smoothness values for the coatings correspond well with the gloss results (figure 18 and tables 3-4).

The whiteness values for the coatings containing aluminum phosphate pigment are also comparable to the coatings containing plastic pigment (figure 19 and table 5).

Review of table 6, shows no significant difference between L<*>, a<*>, b<*> color values.

As can be seen from the data, on an effective solids basis, aluminum phosphate pigment provided comparable gloss values to the plastic pigment formulations. The degree of whiteness and L<*>, a<*>, b<*>, for aluminum phosphate pigment were also comparable to the plastic pigment formulations. The rheologies of the coatings containing aluminum phosphate pigment were comparable to coatings containing plastic pigment.

EXAMPLE 2: Comparison of aluminum phosphate pigment with TIO2 pigment

Coatings were prepared according to Table 7. The delaminated clay was dispersed at 68.0% solids under a high shear Cowles dispersing unit. No. 2 the clay pigment was dispersed at 71.8% solids. Although aluminum phosphate pigment and TiO 2 slurries with solids of 34.2% solids and 62.4%, respectively, were redispersed with the high shear Cowles dispersing unit prior to use.

After dispersing the pigments, the other coating components were added with gentle stirring using a mixer in the order listed in Table 8.

A 26% starch solids solution was prepared by adding dry Penford Gummi 280 to a stainless steel beaker of cold water with stirring. The beaker was placed on a steam table and the mixture heated to 190°F for 30 minutes. After combining all the coating components, the solids content of the coatings was measured. These values are reported in table 9. The Brookfield viscosities for the coatings are also shown in table 9.

Coatings were applied to an uncoated 32.0 gsm wood-containing paper (dried) at 1500 fpm on a cylindrical laboratory coater, CLC. The raw paper had the following characteristics: basis weight: 31.8 gsm (dried) and 34.25 gsm (air dry-7.2% moisture); smoothness: 4.61 microns ± 0.27; Opacity: 72.56% ± 1.88. The CLC was set up using a 0.020 inch coating blade, 0.025 inch support blade and 0.625 inch extension. Coatings were applied at 6.0 + 0.5 gsm. After coating, the samples were cut and conditioned to TAPPI standards. After conditioning, the optical properties (opacity, gloss, whiteness and L, a, b) and smoothness were measured according to TAPPI standard test methods. Smoothness was measured using a Parker Print Surface tester. The samples were then calendered through 2 nips against the steel roll at 155°F and 1200 pli.

Figures 20 and 21 and Table 10 show the gloss to improve with the addition of aluminum phosphate pigment. A significant improvement in gloss was achieved by completely replacing the TiO2 with aluminum phosphate pigment.

The degree of whiteness of the coating decreased with the addition of aluminum phosphate pigment as can be seen in figure 22 and table 11.

As can be seen from Figure 23 and Table 12, the smoothness did not have much effect.

The replacement of Ti02 with aluminum phosphate pigment did not significantly lower the opacity of the coatings, as can be seen from figure 24 and table 13.

The results indicate that aluminum phosphate pigment is a suitable 1:1 substitute for TiO2 as an opacifying agent and a better gloss pigment. The further increase in gloss may result in less calendering pressure being required to achieve a desired gloss level.

The ability to achieve equal gloss at lower calendering pressures would result in higher opacity, whiteness and greater rigidity. All of these have significant benefits for the paper manufacturer.

The L<*> values followed the whiteness values, as both decreased with the addition of aluminum phosphate pigment. The a<*> and b<*> values were not significantly affected.

The data indicate that aluminum phosphate pigment is a suitable 1:1 substitute for TiO2 as an opacifying agent and is a better gloss pigment. The further increase in gloss may result in less calendering pressure being required to achieve a desired gloss level. The ability to achieve equal gloss at lower calendering pressures would enable the retention of more opacity, whiteness and stiffness. It is the desire of the paper manufacturer that all of these are preserved.

EXAMPLE 3: Optical whitening agent study on a coated free sheet

Coatings were prepared according to the formulations given in Table 15 and the order of addition given in Table 16.

The GCC, HydroCarb 90, was dispersed at 72% solids using a high shear Cowles dispersing unit for 20 minutes. After 20 minutes of dispersion, dry FinnFix CMC was added to the GCC and the mixture allowed to disperse for a further 5 minutes. As the CMC thickened, the pH of a 70% solids No. 1 coating clay, Hydrafine, was adjusted to a pH = 8 using ammonium hydroxide. This was done to prevent pigment shock when added to the GCC. The camp was then added to the GCC. After dispersing for 5 minutes, the thickened pigment suspension was then moved to a mixer where the SB latex was added.

As shown in Table 15, formulation #1 was prepared without aluminum phosphate pigment. In the next two formulations, 5 and 10 parts of No. 1 the clay substituted with aluminum phosphate pigment. Concentrate blends were prepared in accordance with Figures 25, 26 & 27. Concentrate blends, MB, of coating formulations 1, 2 & 3 were prepared to ensure that all 8 coatings prepared with and without OBA and PVOH were at similar solids. The PVOH and the OBA (LeucophorHOO HQ and Luecophor BCW liquid, tetrasulfo and hexasulfo, respectively) were added to a pre-weighed amount of coating taken from the MB. The OBA was added last. The PVOH was added at 30% solids. The PVOH used was Celvol 203. After mixing, the solids in the coatings were measured. These values are reported in table 17.

A total of 24 coatings were applied and tested.

The coatings were applied to an uncoated, 61.5 gsm, OBA free sheet with a cylindrical laboratory coater, CLC, at 3000 fpm. A coating weight of 10 ± 0.5 gsm was targeted. The raw paper characteristics are summarized in table 18.

Figures 28 and 29 and table 19 show a slight increase in degree of whiteness with the addition of Pigment X, for both OBAs used. The addition of 1 part PVOH improved the degree of whiteness somewhat. The hexasulfo OBA improved the degree of whiteness more than the tetrasulfo OBA.

I I 1 1 1 ■ ■

Change in fluorescence count is reported for each coating in Figures 30 and 31 and Table 20. The increase in fluorescence count indicates the improvement in whiteness due to the OBA.

A comparison of Figures 6 and 7 shows an improvement in fluorescence counts with the addition of PVOH and no significant decrease in fluorescence counts with the addition of Pigment X. So unlike TiO 2 , Pigment X does not interfere with the OBA. This is because, unlike Ti02, Pigment X does not absorb UV light. The opacifying properties of Pigment X are believed to result from the entrapment of air in the micro-cavities of its structure. These small air pockets diffract light and increase the opacity of the coating layer.

A comparison of the degree of whiteness of the control coatings with PVOH and Pigment X substituted coatings without PVOH reveals that equal degrees of whiteness can be achieved. This finding indicates an advantageous cost saving for the one formulating the coating.

Table 21 provides data for L<*>a<*>b<*> color values with and without the addition of PVOH.

As seen from the data, at the lower level of OBA addition, the hexasulfo OBA performed better. The addition of PVOH improved the whiteness of the coatings. Aluminum phosphate pigment did not interfere with the OBA and it may eliminate the need for PVOH.

While the subject matter has been described with respect to a limited number of embodiments, the specific characteristics of one embodiment should not be attributed to other embodiments of the invention. No single embodiment is representative of all aspects of the invention. In some embodiments, the compositions or methods may include additional compounds or steps not mentioned herein. In other embodiments, the compositions or methods do not include, or are substantially free of, any compound or step not specified herein. Variations and modifications from the described embodiments exist. Finally, any number shown herein should be interpreted as meaning approximate value, regardless of whether the word "about" or "approximately" is used to describe the number. The attached claims are intended to cover all the modifications and variations that fall within the scope of the invention.

Claims (54)

1. Coated paper comprising a coating composition on at least one side of a base paper, wherein the coating composition comprises an amorphous aluminum phosphate or polyphosphate pigment. 2. Coated paper according to claim 1 comprising from about 5 g/m<2> to about 30 g/m<2> of the coating composition. 3. Coated paper according to claim 1, wherein the coating composition further comprises an additive. 4. Coated paper according to claim 2, wherein the additive is selected from the group consisting of binders, lubricants, dispersants, leveling agents, antifoams, wetting agents, optical brighteners, biocides, crosslinking agents, water retention agents, viscosity modifiers and thickeners and combinations thereof. 5. Coated paper according to claim 1, wherein the pigment is present in an amount greater than about 1%, 3%, 5%, 10%, 12%, 15%, 20%, 30% or 50% based on the total weight of solids in the composition. 6. Coated paper according to claim 1, wherein the pigment has a skeletal density of between 1.95 and 2.50 grams per cubic centimeter and a phosphorus to aluminum molar ratio of 1. 7. Coated paper according to claim 1, wherein the pigment comprises 1 to 4 closed cavities per particle. 8. Coated paper according to claim 1, wherein the pigment is characterized by particle size distribution between about 0.1 to about 5 microns. 9. Coated paper according to claim 8, wherein the pigment is characterized by a particle size distribution between about 0.2 to about 0.6 microns. 10. Coated paper according to claim 8, wherein the pigment is characterized by a particle size distribution between about 0.6 to about 1.5 microns. 11. Coated paper according to claim 8, wherein the pigment is characterized by a particle size distribution between about 1.0 to about 3.0 microns. 12. Coated paper according to claim 1, wherein the pigment is characterized by an average individual particle radius size of between about 10 and 80 nanometers, when in dry powder form. 13. Coated paper according to claim 4, wherein the binder is selected from the group consisting of a protein, starch, rubber, resin, emulsion polymer or a combination thereof. 14. Coated paper according to claim 1, wherein the coating composition further comprises one or more additional pigments) selected from the group consisting of calcium carbonate, calcined kaolin, hydrous kaolin, porcelain earth, talc, mica, dolomite, silica, silicates, zeolite, gypsum, satin white, titanium oxide, titanium dioxide, calcium sulfate, barium sulfate, aluminum trihydrate , plastic pigment and combinations thereof. 15. Coated paper according to claim 14, wherein the additional pigment is TiO 2 . 16. Coated paper according to claim 15, wherein the coating composition comprises the amorphous aluminum phosphate or polyphosphate pigment in an amount from about 1% to about 40%, and the TiCV pigment in an amount from about 1% to about 40% based on the total weight of solids in the composition. 17. Coated paper according to claim 15, wherein the coating composition comprises the amorphous aluminum phosphate or polyphosphate pigment and the TiO 2 pigment in a ratio of about 1:1. 18. Coated paper according to claim 15, wherein the coating composition comprises the amorphous aluminum phosphate or polyphosphate pigment and the TiO 2 pigment in a ratio of about 1:2. 19. Coated paper according to claim 1, wherein the coated paper is selected from the group consisting of a coated color copy paper, coated xerography paper, coated screen printing paper, coated gravure paper, coated sublimation technique paper, coated flexography paper, coated inkjet printing paper, coated photographic paper, coated web offset printing paper, coated electrophotographic printing paper, coated image registration paper for thermal transfer registration, coated ink jet registration paper and combinations thereof. 20. Coated paper according to claim 1, wherein the coated paper is a coated inkjet paper or coated digital printing paper. 21. Coated paper according to claim 1, wherein the coated paper is a coated publication paper. 22. Coated paper according to claim 1 which has a coating gloss equal to or greater than about 20% at 75° measured by TAPPI test method T480 om-92. 23. Coated paper according to claim 1 having a coating gloss of from about 25% to about 75% at 75°. 24. Coated paper according to claim 1 having a smoothness of less than 5.0 as measured using TAPPI test method for Parker Print Surface: T555 om-99. 25. The coated paper of claim 1 having a smoothness of from about 1.0 to about 2.5 as measured using the TAPPI test method for Parker Print Surface: T555 om-99. 26. Coated paper according to claim 1 having an opacity of more than 80% as measured using TAPPI test method T425 om-91. 27. Coated paper according to claim 1 having the opacity from about 85% to about 99% as measured using TAPPI test method T425 om-91. 28. Coated paper according to claim 1 having a degree of whiteness greater than about 70% GE degree of whiteness as measured using TAPPI test method T452 of 92. 29. Coated paper according to claim 1 having a degree of whiteness from about 70% whiteness to about 95% GE whiteness as measured using TAPPI test method T452 about 92. 30. Method for producing a coated paper comprising applying a coating composition to at least one side of a raw paper, wherein the coating composition comprises an amorphous aluminum phosphate or polyphosphate pigment. 31. Method according to claim 30, wherein the amorphous aluminum phosphate or polyphosphate pigment is prepared by combining starting materials comprising phosphoric acid, aluminum sulfate and sodium hydroxide. 32. Method according to claim 31, in which the starting materials are combined simultaneously. 33. Method according to claim 31, wherein the starting materials react to form an amorphous aluminum phosphate or polyphosphate precipitate, wherein the precipitate is dried at a temperature of less than about 130°C, and wherein amorphous aluminum phosphate or polyphosphate particles formed during drying have one or more closed voids per particle. 34. Method according to claim 33, wherein the particles are essentially without open pores. 35. Method according to claim 31, in which the starting materials are combined together for about 30 minutes to form an amorphous aluminum phosphate or polyphosphate precipitate. 36. Method according to claim 30, wherein the amorphous aluminum phosphate or polyphosphate pigment is prepared by combining starting materials comprising phosphoric acid, aluminum hydroxide and sodium aluminate. 37. Method according to claim 36, wherein the phosphoric acid and aluminum hydroxide are combined in a first step to produce an acidic aluminum phosphate solution or suspension, and the sodium aluminate is added to the solution or suspension in a second step. 38. Method according to claim 36, in which the phosphoric acid, aluminum hydroxide and sodium aluminate are combined in a single step. 39. Method according to claim 36, wherein the starting materials react to form an amorphous aluminum phosphate or polyphosphate precipitate, wherein the precipitate is dried at a temperature of less than about 130°C, and wherein amorphous aluminum phosphate or polyphosphate particles formed during drying have one or more closed voids per particle. 40. Method according to claim 39, wherein the particles are essentially without open pores. 41. Method according to claim 31 which further comprises calendering the coated paper to form a coating on it. 42. Method according to claim 31, wherein the composition further comprises water. 43. Method according to claim 31, wherein the composition further comprises an additive. 44. Method according to claim 31, wherein the composition further comprises one or more additional pigment(s) selected from the group consisting of calcium carbonate, calcined kaolin, hydrous kaolin, porcelain earth, talc, mica, dolomite, silica, silicates, zeolite, gypsum, satin white, titanium oxide, titanium dioxide, calcium sulfate, barium sulfate , aluminum trihydrate, plastic pigment and combinations thereof. 45. Method according to claim 31, wherein the composition is applied to the base paper in an amount of from about 5 g/m<2> to about 30 g/m<2>. 46. A high bulk coated paper comprising a base paper having a weight of 18 to 34 pounds per pad and a coating composition on at least one side of the base paper, wherein the composition comprises an amorphous aluminum phosphate or polyphosphate pigment, and the coating composition has a weight of not more than 3 pounds per rice per page, and the base paper has a thickness of at least about 88% of the total thickness of the coated paper and the coating composition provides substantially the remainder of the thickness of the coated paper, such that the coated paper has a bulk factor of at least 55. 47. Coated paper according to claim 46, wherein the amorphous aluminum phosphate or polyphosphate pigment is prepared by combining starting materials comprising phosphoric acid, aluminum sulfate and sodium hydroxide. 48. Coated paper according to claim 46, wherein the amorphous aluminum phosphate or polyphosphate pigment is prepared by combining starting materials comprising phosphoric acid, aluminum hydroxide and sodium aluminate. 49. A light weight, high bulk coated paper comprising a base paper having a weight of about 26 to 36 pounds per rice, and a coating composition on at least one side of the base paper, wherein the composition comprises an amorphous aluminum phosphate or polyphosphate pigment, and the coating composition has a weight of about 1.5 to 3.5 pounds per rice per page, and the base weight and coating weight are selected such that the base has a thickness of at least about 75% of the total thickness of the coated paper and the coating composition provides substantially the remainder of the thickness of the coated paper, so that the coated paper has a bulk factor of at least 55. 50. Coated paper according to claim 49, wherein the amorphous aluminum phosphate or polyphosphate pigment is prepared by combining starting materials comprising phosphoric acid, aluminum sulfate and sodium hydroxide. 51. Coated paper according to claim 49, wherein the amorphous aluminum phosphate or polyphosphate pigment is prepared by combining starting materials comprising phosphoric acid, aluminum hydroxide and sodium aluminate. 52. An ultralight weight, high bulk coated paper comprising a base paper base having a weight on the order of about 18 to 24 pounds per pad, and a coating composition on at least one side of the base paper, wherein the composition comprises an amorphous aluminum phosphate or polyphosphate pigment, and the coating composition has a weight of about 2 pounds per rice per page, and the base weight and coating weight are selected such that the base has a thickness of at least about 75% of the total thickness of the coated paper and the coating composition provides substantially the remainder of the thickness of the coated paper , so that the coated paper has a bulk factor of at least 55. 53. Coated paper according to claim 52, wherein the amorphous aluminum phosphate or polyphosphate pigment is prepared by combining starting materials comprising phosphoric acid, aluminum sulfate and sodium hydroxide. 54. Coated paper according to claim 52, wherein the amorphous aluminum phosphate or polyphosphate pigment is prepared by combining starting materials comprising phosphoric acid, aluminum hydroxide and sodium aluminate.